Polyacetylene tetrapolymers

ABSTRACT

Certain polyacetylenes are provided having chemically combined ether linkages, or alkylene linkages and mixtures thereof, exhibiting improved compatability with various organic plasticizers. The polyacetylenes have been found to be melt extrudable, and convertible to carbonaceous films and molded carbon objects.

This application is a division of Ser. No. 330,497, filed Feb. 8, 1973,now U.S. Pat. No. 3,816,374, which in turn is a continuation-in-part ofapplication Ser. No. 118,467, filed Feb. 24, 1971, now abandoned, andassigned to the same assignee as the present invention.

The present invention relates to certain polyacetylenes useful formaking carbonaceous films and fibers.

Prior to the present invention, various attempts were made to carbonizenumerous organic polymers in fibrous form having a high carbon contentto provide for high strength graphite fibers. As shown in Johnson, etal, U.S. Pat. No. 3,412,062, for example, carbon fibers having a hightensile strength and Young's modulus can be made from polyacrylonitrile.Although desirable results can be achieved with polyacrylonitrilefibers, these fibers must be subjected to a preliminary oxidationtreatment to stabilize the fibers prior to graphitization. Although thepreoxidation treatment results in fiber stability, it also can result inconsiderable fiber weight loss and reduction in carbon values. It isgenerally known that polyacetylenes, for example, polymers shown by HayU.S. Pat. Nos. 3,300,456; 3,332,916; 3,519,611, British Patent1,149,697, etc. can be converted to the carbonaceous state withoutsignificant reduction in weight or loss of carbon values. In order toconvert such polyacetylenes to carbon and graphite fiber, it isnecessary to produce a precursor fiber which can be carbonized. Directheating of polyacetylenes to permit extrusion of polymer having beenunsuccessful because the acetylenic bond can be activated attemperatures above 150° C. rendering the polymer intractable. Effortsutilizing various organic solvents as plasticizers often have beenunsuccessful, due to such factors as plasticizer incompatibility,volatility, etc.

The present invention is based on the discovery that certainpolyacetylenes defined hereinafter, exhibit optimum compatibility whenemployed with a variety of organic plasticizers, such as Arochlors,nitrobenzene to produce melt-extrudable blends. The melt-extrudableblends can be converted to polyacetylene fibers. These polyacetylenefibers can be converted to high strength graphite.

There is provided by the present invention polyacetylene terpolymersselected from the class consisting of

A. terpolymers consisting essentially of

A. 85 to 92 mole percent of meta-diethynylbenzene units,

B. 4 to 10 mole percent of para-diethynylbenzene units,

C. 2 to 6 mole percent of bisphenol-A dipropargyl ether units, where thesum of (a), (b) and (c) units in (A) is 100 mole percent, and

B. terpolymers consisting essentially of

D. 74 to 86 mole percent of meta-diethynylbenzene units,

E. 4 to 9 mole percent of para-diethynylbenzene units, and

F. 5 to 15 mole percent of diethynylalkane units, where the sum of (d),(e) and (f) units in (B) is 100 mole percent, and

C. tetrapolymers consisting essentially of about 5% by weight ofacetylene units, and 95% by weight of (A) or (B), based on the totalweight of tetrapolymers.

The polyacetylene terpolymers of the present invention can be made byreacting ethynylarylene compounds such as mixtures ofmeta-diethynylbenzene with para-diethynylbenzene in combination withcompounds such as dipropargyl ethers, diethynyl alkanes, and optionallywith acetylene. The oxidative coupling reaction disclosed in Hay U.S.Pat. No. 3,300,456, assigned to the same assignee as the presentinvention can be employed. There is employed in the oxidative couplingreaction, which will be shown more specifically in the examples setforth later, a basic cupric amine complex, and oxygen. A mixture, forexample, a dihydric phenol can be employed with a diethynyl arylenemixture consisting for example, of meta-diethynylbenzene andpara-diethynylbenzene and employed in an oxygenated solution with anoxidative coupling catalyst such as cuprous chloride, N, N, N',N'-tetramethylethylenediamine with an appropriate organic solvent suchas dichlorobenzene and pyridine. Recovery of the terpolymer can beachieved by the addition of the reaction mixture to methanol containinga trace of hydrochloric acid. The resulting terpolymer can thereafter bewashed by conventional means with a solvent such as methanol andthereafter dried. When employing dipropargyl ether units in the reactionmixture, there is produced "ether terpolymers" while "alkaneterpolymers" can be made by using diethynyl alkane compounds such as1,6-diethynylhexane, 1,4-diethylbutane, etc.

In order that those skilled in the art may be better able to practicethe invention the following examples are given by way of illustration,and not by way of limitation. All parts are by weight.

EXAMPLE 1

A terpolymer was made by employing dipropargyl ether of2,2-bis(4-hydroxyphenyl)propane (bisphenol-A) (BPA),meta-diethynylbenzene (MDEB), and para-diethynylbenzene (PDEB) utilizingan oxidative coupling catalyst produced with cuprous chloride,N,N,N',N'-tetramethylethylenediamine, and a solvent system of pyridineand dichlorobenzene.

There was added a solution in about 25 parts of dichlorobenzene of 0.5parts of the dipropargyl ether of BPA, 4.1 parts of MDEB, and 0.4 partsof PDEB to a mixture of 0.15 parts of cuprous chloride, about 0.18 partsof N,N,N',N'-tetramethylethylenediamine dissolved in an oxygenatedsolution of about 1.7 parts of pyridine and 75 parts ofortho-dichlorobenzene at 60° C. The temperature of the mixture rose to88.5° C. while it was stirred after about 2 minutes. The mixture alsobecame too thick to stir. After 10 minutes the mixture was allowed tocool at room temperature, and added to excess methanol containing atrace of hydrochloric acid. There was obtained a quantitative yield ofproduct having an intrinsic viscosity in ortho-dichlorobenzene at 120°C. of 0.77 dl/g. Based on method of preparation the product was apolyacetylene terpolymer having about 4 mole percent dipropargylbisphenol-A ether units, 9 mole percent of PDEB units and 87 molepercent of MDEB units.

Compatibility of the terpolymer was determined by forming a 2% solutionof the terpolymer in ortho-dichlorobenzene at temperatures of about 110°C. and allowing the solution to cool. If precipitation started to occurat 55° C. or above, that is, if the solution became hazy, then theterpolymer was considered incompatible. Two undersirable consequencescan result from incompatibility. First, a higher than normal extrusiontemperature can be required. Second, low molecular weight polymer wouldlikely form during oxidative coupling due to premature precipitation ofpolymer. Low molecular weight, i.e., an intrinsic viscosity below 0.5dl/g in ortho-dichlorobenzene would not likely form satisfactorypolyacetylene fiber convertible to high strength graphite.

The above solution terpolymer was found to be compatible since it becamehazy at about 38° C. It also was found that the terpolymer resulted inless than 7% loss by weight of carbon values based on the theoreticalweight percent of carbon, when the terpolymer was subsequentlygraphitized in fibrous form.

The terpolymer is blended with ortho-dichlorobenzene utilizing 2 partsof plasticizer, per part of terpolymer. The blend is extruded to produce2 mil diameter extrudate. The extrudate is heated slowly to atemperature of 300° C. The resulting heat treated fiber is then stressgraphitized at from 4,000 to 14,000 psi at temperatures up to 3,000° C.in an argon atmosphere. High strength graphite is obtained having atensile of 330 × 10³ psi.

EXAMPLE 2

A solution of 0.5 parts of 1,7-octadiyne, 4.2parts of MDEB and 0.3 partsof PDEB in 25 parts of ortho-dichlorobenzene was added to a solution of0.15 parts of cuprous chloride, about 0.23 parts ofN,N,N',N'-tetramethyl-1,2-ethylene diamine and about 1.7 parts ofpyridine, in about 75 parts of ortho-dichlorobenzene, which was beingoxygenated and stirred at 621/2° C. The temperature of the mixture roseto about 88° C. within 2 minutes and then gradually dropped. The mixturewas stirred for 60 minutes and then poured into about 500 parts ofmethanol containing a trace of hydrochloric acid. The product whichprecipitated was collected on a filter and washed with additionalmethanol and dried at 25° C. There was obtained a 99% yield of producthaving an intrinsic viscosity of 0.50 dl/g at 120° C. Based on method ofpreparation, the product was polyacetylene terpolymer composedessentially of 12 mole percent of octadiynyl units, 82 mole percent ofMDEB units, and 6 mole percent of PDEB units.

Several additional alkylene terpolymers were made following the sameprocedure to determine the optimum mole percent ranges of ethynyl unitsfor plasticizer compatibility, as determined in ortho-dichlorobenzene.It was found that optimum compatibility in ortho-dichlorobenzene basedon the test of Example 1, was a terpolymer having 15 mole percent ofalkane diethynyl units, 76 mole percent of MDEB units, and 8 molepercent of PDEB units.

A weight loss of less than 5% was experienced when the terpolymers weregraphitized as described in Example 2. There was obtained high strengthgraphite fiber useful for making composites with epoxy resins.

EXAMPLE 3

There was added a solution of 4.23 parts of MDEB, 0.27 part of PDEB,0.50 part of the dipropargyl ether of BPA in ortho-dichlorobenzene to anoxygenated mixture of 0.15 part of cuprous chloride, 0.17 part oftetramethylethylenediamine, about 1.7 part of pyridine, andapproximately 60 parts of ortho-dichlorobenzene. Oxygenation of themixture was achieved by bubbling oxygen into the solvent at a rate ofabout 0.5 cubic feet per hour, per mole of ethynyl compound. There wasthen bubbled into the mixture 0.28 part of acetylene over a 2 minuteperiod. The reaction temperature rose steadily from an initial bathtemperature of about 61° C. to about 80.5° C., and then graduallydropped. External heating was removed after about 6 minutes, after whichtime the oxygenation of the mixture was discontinued. The product beganto precipitate upon cooling. The mixture was added to excess methanolacidified with hydrochloric acid to effect the precipitation of product.Recovery of the product was achieved by a standard extraction technique,followed by washing the methanol. Based on method of preparation, theproduct was a polyacetylene having about 95% by weight of diethynylunits consisting of 4 mole percent of chemically combined dipropargylbisphenol-A ether units, 9 mole percent of PDEB units, 87 mole percentof MDEB units, and about 5 percent by weight of additional acetyleneunits based on the weight of polyacetylene. The product had an intrinsicviscosity in dichlorobenzene at 120° C. of 1.12 dl/g. It did notprecipitate from a 2% solution in ortho-dichlorobenzene until cooled to30° C.

EXAMPLE 4

There was added a mixture of 8.58 g. of MDEB, 0.95 g. of PDEB, and 0.47g. of dipropargyl ether of BPA in 16 ml of ortho-dichlorobenzene to anoxidative coupling catalyst reaction mixture of 100 ml. ofortho-dichlorobenzene, 3.4 ml. of pyridine, 0.46 ml. ofN,N,N',N'-tetramethyl-1,2-ethylenediamine, and 0.30 g. of cuprouschloride. During the addition of the aforementioned monomer solution,oxygen was bubbled into the mixture at a rate of 1 cubic foot per hour,while the temperature of the mixture was maintained at 60° C. withstirring.

The reaction temperature rose to 83° C. within 6 minutes and thengradually dropped. After 17 minutes the mixture was too viscous to stir.Thereupon, 75 ml. of hot ortho-dichlorobenzene was added to the mixturewhich was allowed to cool. Upon cooling the product precipitated whichformed viscous slurry. It was poured into 1400 ml. of methanolcontaining 15 ml. of concentrated hydrochloric acid. The product wasfiltered and stirred two additional times in methanol. The product wasdried overnight under reduced pressure. There was obtained 9.41 g. ofproduct. Based on method of preparation, the product was a polyacetyleneterpolymer consisting of 88 mole percent of MDEB units, 10 mole percentof PDEB units and 2 mole percent of dipropargyl ether units of BPAD. Theabove procedure was repeated to produce two additional polyacetyleneterpolymers consisting of 91.3 mole percent of MDEB units, 4.7 molepercent of PDEB units, and 4 mole percent of dipropargyl ether units ofBPAD; 90 mole percent of MDEB units, 4 mole percent of PDEB units, and 6mole percent of dipropargyl ether units of BPAD, respectively. The hazetemperature of the aforementioned polymer was determined in accordancewith the procedure of Example 1, using a 2% polymer solution inortho-dichlorobenzene. It was found that the terpolymer having 2 molepercent of BPAD dipropargyl ether units was 48° C. and the hazetemperature of the terpolymers having 4 and 6 mole percent of BPAD unitsrespectively, was 49° C. It was also found that a terpolymer having aslittle as 85 mole percent of MDEB units, 10 mole percent of PDEB units,and 5 of BPAD, had a haze temperature of less than about 40° C.Copolymers of MDEB and PDEB free of BPAD units such as a 80 MDEB/20 PDEBcopolymer blend were insoluble in ortho-dichlorobenzene even at 150° C.which is near the decomposition temperature of the polymer and a hazetemperature could not be determined. It was also found that when theBPAD units and the terpolymer blend substantially exceeded 6 molepercent such as 10 mole percent, a dramatic increase in the weight lossof the polymer (12%) was experienced when it was heated to a temperatureof 900° C. at a rate of 10° per minute.

Although the above examples are limited to only a few of the very manyterpolymers which are included within the scope of the presentinvention, it should be understood the terpolymers described prior tothese examples, as well as recited in the claims, also fall within thescope of the invention.

What we claim as new and desire to secure by Letters Patent of theUnited States:
 1. Polyacetylene tetrapolymers consisting essentially offrom about 5% by weight of acetylene units and 95% by weight of amixture of units consisting essentially of 74 to 86 mole percent ofmeta-diethynylbenzene units, 4 to 9 mole percent ofpara-diethynylbenzene units and 5 to 15 mole percent of diethynylalkaneunits, where the sum of the units in said mixture of units is 100 molepercent.